All You Need to Know About LED Street Light Control Systems

Dimming control and maintenance are crucial after installing street lamps and require a lot of labor costs. You can controll LED street lights through:

  • Photocell switch on/off
  • Timing Dimming
  • Smart Controller system

ADNLITE will discuss the advantages and disadvantages of these control methods in this article. This information will help choose the appropriate control method for road lighting projects.

What is a Photocell?

Photocell is also called a light sensor switch or dark-to-dawn sensor. It can turn on or off street lights according to the presence and brightness of natural light. This all happens automatically, without human intervention. So, if a street lamp is not equipped with Photocell, you need to turn it on and off through the main switch manually.

Principle of Photocell

The induction head is connected to the joint dimming switch of the street light power supply. The sensing head usually has photosensitive electronic components. The photosensitive electronic components change the voltage or current value based on the brightness of natural light. The sensor switch changes the current or voltage, and the street light power supply turns the LED light source on or off.

When installing street lights and photo-sensitive switches, choose from the following sockets:

  • 3-pin Nema socket
  • 5-pin Nema socket
  • 7-pin Nema socket

It will meet the need for outdoor waterproofing.
Check whether the photo-sensitive switch accepts natural light when installing street lights. Clean the surface of the sensor switch regularly. It will avoid the influence of foreign objects such as leaves.

Additional Cost of Installing Photocell for Street Lights

An optical switch and waterproof base usually cost around $6. Be guided that installing the photosensitive switch also requires additional processes. It might include opening holes in the back of the street lamp housing. Therefore, from the factory production perspective, installing an optical switch will cost between $8 to $10.

Malfunctioning Photocell

You might encounter some issues in your solar street light’s photocell but do not worry. In most cases, if the solar street light is placed near the highway, it may accumulate dust from the road. The huge peck of accumulated dust on your solar lamps can cover the sensor head after a long time. Not cleaning it will prolong the solar lamp’s lighting time as it will not detect enough natural light.
Leaves or surrounding buildings can cause street lights to turn on during the day due to shading. Streetlights can also turn off at night due to external light sources. Such as car lights shining on the sensor head.

What is the Timing Dimming Control System?

The Timing Dimming Control system is a functional module of the street lamp power supply. After a long time and the street light brightness is set, everything can remain the same. For example, within 6 hours after the lights are turned on when traffic flow is at peak, and the LED power is set to 100%. After 6-10 hours in the middle of the night, the LED power will be set to 50% to save energy. This mode times the street lights from the moment they turn on. The system cannot be adjusted for seasonal changes..

Some brands of timed dimming control systems have automatic adjustments. This is the case with Philips and Osram, for example. The system adjusts the dimming point in the second half of the night. It is based on the sunset and sunrise conditions of the previous two days. The lighting schedule of streetlights varies throughout the seasons.

DateSunset (turn on)Lighting Curve
1st Jan17:0517:05-23:5623:56-03:5603:56-sunrise
1st Apr19:2419:24-23:5823:58-03:5803:58-sunrise
1st Jul21:0221:02-23:5723:57-03:5703:57-sunrise
1st Oct18:3318:33-23:4323:43-03:4303:43-sunrise

The Disadvantage of Using Timing Dimming Controls Only

If a street light only has the function of time dimming, it cannot be perfect in the following situations. In rainy weather, if the natural light is too dark during the day, the street lamps will not light. Remember that the times of sunrise and sunset vary with the seasons. But, the time of street lamp time-controlled dimming is fixed.

So, in this case, you cannot adjust the dimming settings of the street lamps based on seasonal changes. Therefore, the combination of light-controlled switches and time-controlled dimming is a must. These two functions enable street lights to adjust the dimming schedule automatically according to seasonal changes.

What is Smart Control System?

The intelligent control system can control, monitor and manage each lamp remotely. This system allows municipal street lights to be monitored and controlled from the center and field by remotely distributed RTU via GPRS/CDMA mobile communication network. The system can monitor the operation of each lamp. It includes voltage, current, power, power factor, power consumption, and lamp fault data.

Benefits of Smart Control System

  1. Smart control system reduces labor costs. Usually, the distribution of street lamps is scattered, and the number is large. You need to invest a lot in the manual inspection cost and replacement of lamps every year! But with street light intelligent control systems, you can save labor, management, and vehicle inspection costs.
  2. To use the original clock control mode, the time setting of the clock controller must be periodically adjusted to turn on the light.. Due to limited manpower, the adjustment cycle should not be too short, generally 1-2 times a month. This will allow about 15 minutes of headroom for each adjustment. With that, it turns on 15 minutes earlier and turns off 15 minutes later, totaling about 30 minutes. In this way, the lights are turned on for an average of about 30 minutes a day during each adjustment cycle, which undoubtedly wastes energy.
  3. According to the road traffic conditions, the brightness of the street lights can be automatically adjusted. It can save 30 to 40% of the electricity bill.
  4. Save electricity by eliminating abnormal lighting during the day. It can save a lot of workforce and material resources and reduce considerable expenses. The conclusion comes from empirical data from the street lighting industry.

Three Major Sections of Smart Street Lamp Control

1.Monitor Control Center

The monitoring center is the office where lighting managers monitor and control street lights. Managers can access and control through the master software.
Control objects: lighting transformers/distribution cabinets and street lights
Control content: on/off light command sending, parameter configuration, status query, fault detection
Other available: operation status of lighting equipment in the city/district

2.Centralized Controller

The centralized controller is installed in the distribution cabinet to manage the line. It receives commands from the monitoring center through wireless GPRS. At the same time, it uses power carrier technology to send commands and information feedback to the single light terminal. This control method can realize the control of single street lights. It can also collect various status information on the line. In case of communication failure with the monitoring center, the controller can automatically perform light switching operation according to the preset time curve. The centralized controller can be connected to the single light controller.

3.Single lamp controller

The single lamp controller is installed on the street lamp pole and used together with the Centralized Controller. The device adopts power carrier technology. It receives instructions from the monitoring center through the Centralized Controller. It helps to realize switching lights and voltage regulation at the single-light level. Also, the single-lamp controller can actively collect single-lamp fault information for reporting. Thus, the entire control system can realize the following functions:

  • Single-lamp networking
  • Single-lamp control
  • Single-lamp energy saving
  • Single-lamp data collection
  • Single-lamp electric energy metering


The table below is a summary of the three street lamp dimming control methods.

ControlPhotocell switchTiming dimmingSmart control system
AdvantageReduce labor; can adapt to the season to automatically switch operations.Save electricity; no extra cost.Smart, Save a lot of operation and maintenance labor costs
DisadvantageRequires additional cost; easily disturbed by the external environment.Not smarterThe cost is high and the operation is relatively complicated